Live Port shifting with difrent delay mega32

while (1)
          {
	if((t1 % 63) == 0 ){/////////////////PORTA shift
                    PORTA = a;
                     a <<= 1;
                     if(a==0)
                    a = 0b00000001;
                    }
	 if((t1 % 171) == 0 ){/////////////////PORTB shift
                    PORTB = b;
                     b <<= 1;
                     if(b==0)
                    b = 0b00000001;
                    }
	 if((t1 % 342) == 0 ){/////////////////PORTC shift
                    PORTC = c;
                     c <<= 1;
                     if(c==0)
                    c = 0b00000001;
                    }
	 if((t1 % 511) == 0 ){/////////////////PORTD shift
                    PORTD = d;
                     d <<= 1;
                     if(d==0)
                    d = 0b00000001;
		    t1 = 0;
                    }

delay_ms(1);
             t1++;

}   }